Electromechanical telephone system



June 16, 19.25. 1,541,779

F. ALDENDORFF sucrnorcnmrcn. reunion: s'sx'sn Filed No. 16. 1922 8 Sheets-Sheet 1 '-J ich: \crF Kore June 16, 1925.

F. ALDENDORFF ELIGTROIECHANICAL TILBPBOII SYSTII Filed Nov. 16. 1922 8 Sheets-Sheet 5 F1 g, lia.

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June 16, 1925.

Ju'ne 16,. 1925. A 1,541,779

A F. ALDENnoRFF BLIGTROIECHANIOAL TELEPHONE SYSTII Filed Nov. 16. 1922 8 Sheets-Sheet 5 Fig "5a u1 95 21.5 4 9 9 A# "n nooo l auw ., I o o Q I m June 16, 1925. 1,541,779

F. ALDENDQRFP Enzernoutcxmxcn. Tennyson: ssm

Filed Nov. 16, 1922 8 Sheets-Sheet 6'- Fz'kgib.

2.85 Ar 2615 aez June 16, 1925.

l y 1,541,779 F. ALDENDORFF ELBCZROKECHANICAL TELEPHONE SYSTBK Filed NOV. 16, 1922 8 Sheets-Sheet 7 June 16, 1925. y

F. ALDENDoRr-'F ELICTROIECHMIIGAL TB'LEFHOI SfSTll Filed NOV. 16, i922 Fig. 6b.

LM M5 8 shuts-Sheet 8 @noA --uooo L17-9 Patented June 16, 1925.

FRITZ ALDENDORFF, OF BERLIN-WILMERSDORF, GERMANY, ASSIGNOR TO PAUL KOLSCH, OF NEW YORK, N. Y.

ELECTROMECHANICAL TELEPHONE SYSTEM.

Application lcd November 16, 1922. Serial No, 601,393.

Be it known that I, FRITZ ALDnNnonFF, rcsitling,y at 2? Brabanterstrasse, Berlinlvilmersdorf, (lrermany, have invented certain new and useful Improvements in Electromechanical Telephone Systems, of which the following is a specification.

This invention relates to an electro-mechanical telephone system in which all the switches used have wipers that move in one plane only. An object of the invention is to provide a system in which etticient trunking arrangements can be obtained hy comparatively simple means.

nother feature of the invention relates to novel n'letering arrangements, further feature of the invention consists in providineY wanted line connect-ors whose wipers are set onto any desired set of bank contacts hy means of auxiliary switches which, in addition to designatingr the desired set of hank contacts, assist in performing other functions as for example restoring the switching,T apparatus to its normal position and applying a ringing current to the wantcd suhscril cr`s line.

The invention is illustrated in the drawing' in which Fig. l is a diagram of the general layout of the system,

Fig. 2 is a diagram representing` the groupingof the various switches,

Figi. i3 illustrates how practically any dcsircd trunking' etliciency may loc obtained with the aid of simple switches and Figs. 4a, 4b, 5, 5b and 6a, t", when placed side hy side. represent a completo diagram of the circuits of the switches of Fie'. l.

The snhscrihers` talkingr connections are cstahlishc-d through the voice current; switches CC, GSI, TCT. GSH, TCU, and lYt, Figi. l, and during;r the operation ot' setting; the said switches auxiliary switches, which are only used temporarily, are opv cratcd for the purpose of effectingv rapid connections hctween a calling line or trunk and the next numerical switch ahead and for the additional purpose of guiding,r nonnumerical switches onto a calling line or trunk. Thr` auxiliary. tcmporarily-'uscd switches are the switches Cl?, PT, DTI, tf'l. and lTll, T' l, and IC, llfl, itil. The non-numerical switches are the switches CC.

TCT and TCH, Fig, l. The switches CC,

CF, TCI, DTI, TCH, DTH and TVC will he assumed to have contact banks with one hundred sets of hunk contacts each, while the numerical switches (itil and GSH have only ten scts of hank contacts each. The system shown in Fig. l will he assumed to have a capacity for ten thousand sulosoriloers`r lines divided into ten major groups of one thousand lines cach and each major group will he assun'ied to have 10 minor groups of one hundred lines each.

The `grouping; of the switches and the trnultinnv arrangiemcnts will he explained with the aid of Fig, ln this ligure the rectangle ahovc the double line 1l will be supposed to contain the switches belonging` to the tirst sgroup ot one thousand lines, while the rectangle, helow the douole line ll contains the switches lielonejing to the secontl group ot cnc thousand lines. The rectangles are divided into three columns loy hc vertical lines 1'?, and 1?) and each rectangle l, ll is divided into horizontal ololongrs hy horizontal lines` there heiner ten ohlongrs in cach vertical column of each rcctangle T, li. Pairs 'of switches CC. GSI are shown in the first tive ohlonc's l to 5 of the first vertical column of the rectangle l, and pairs of switches TCT, (tSli TCU, li't are indicated in the first four and two olilong's respectively of the second and third vertical columns ot' the rectangle l. Pairs of switches (ltl. itil TCT, GS11 TIT, Y are also shown in some of the ohlongls of the second rectangle Il. lilach ot the said ohlonirs in an exchange accord in;r to the invention will lic assumed to contain not only onc pair hut ten pairs ot' switches, one pair only heine' indicated in Fie: il for convenience of illustration. The su itches CC, @Si in thc first column arc the ones that complete thc tirst staoc of a con ncction. i. e thc connection hctwcen a callY in; line and thc wanted group of a thousand lilies, thc switches in the .second vcrtical column complete thc second stage of a connection in which thc wanted group ot` one hundred lines reached, and the switches. in the third column complete thc third stage of thc connection in which the callingr party is connected to the wanted line. The `Lroup selectors (itilV hv which the wanted grroup of one thousand lines is seiected have ten se s of hank contacts each and the group selectors GSII are also tenpoint switches. The first group selectors GSI have to enable calling subscribers to select any group of a thousand lines. Hence the ten bank contact sets of each group selector GSI must lead to ten different thousand groups. The wiring between the first group selectors GSI is as follows: The first bank contact set, as 761 of the switch GSI, of each group selector in the oblong I in the first Vertical column of the first thousand group I leads to a bank contact in each of the ten trunk connectors TCI in the first oblong 1 of the second vertical column of the first thousand group I. Thus the ten first contact sets of the group selectors GSI in the first oblong of the first connecting stage are connected to ten trunks which are multiply connected to ten one hundred-point finder switches or primary trunk connectors TGI in the first oblong l of the second connecting stage of the first thousand group I. The ten second contact sets of the first group selectors GSI in the first oblong of the first connecting stage of the first thousand group I are connected to ten trunks which are multiply connected to primary trunk connectors TCI in the first oblong 1 of the second connecting stage of the second thousand group II. The ten third contact sets of the ten first group selectors GSI of the first oblong I of the first connecting stage o t the first thousand group I are connected to ten trunks which are multiply connected to primary trunk connectors in the first oblong of-the third thousand group (not shown) and so on.

The ten first bank contact sets of the first group selectors GSI in the first oblong 1 of the first connecting stage of the secotnl their sand group II are connected to ten trunks which are multiply connected to the bank contacts of' the ten primary trunk connectors TCI in the first oblong 1 of' the second connecting stage of the first thousand group I. The ten second contact sets ofI the ten first group selectors GSI in the first oblong 1 of the first connecting stage of' the second thousand group II are connected to ten trunks which are multiply connected to the bank contacts of the ten primary trunk connectors'TCI in the oblong I of the second connecting stage of the second thousand group II. rIlhe third bank contact sets of the ten first group selectors GSI in the first oblong 1 of the first connecting stage of the second thousand group II are connected to ten trunks which are multiply connected to the ten primary trunk connectors in the first oblong of the second connecting stage of the third thousand group (not shown; and so on.

The ten first bank contact sets of the first group selectors in the second oblong 2 of the first connecting stage of the first thousand group I are connected to ten trunks which are multiply connected to the contact banks of the ten primary trunk connectors in the oblong 2 in the second connecting stage of the first thousand group I; the ten second bank contact sets of the first group selectors in the oblong 2 of the first connecting stage of' the first thousand group I are connected to ten trunks which are multiply connected to the bank contacts of. the primary trunk connectors in the second oblong 2 of the second connecting stage of the second thousand group II, and so on.

From the foregoing description it will be apparent that when a first group selector (ISI connects the calling line through to a trunk leading to the particular thousand group selected the connection will be eX- tended to a trunk in the second connecting stage by any idle one of ten different primary trunk connectors TCI. The connections with the third connecting stage are effected by means of the second group selectors GSII. The Wiring between the second group selectors GSH and the secondary trunk connectors or finders TCII will now be explained: The ten first bank contacts sets of the second group selectors GSII in the first oblong 1 of the second connecting stage of the first thousand group I are connected to ten trunks which are multiply connected to the contact banks of the ten one humlred-point secondary trunk connectors TII of the first oblong 1 of the third connecting stage of the first thousand group I. The ten second bank contact sets of the second group selectors GSII iu tbc first oblong 1 of the second connecting stage of the first thousand group I are connected to ten trunks which are multiply connected to the bank contacts of the ten secondary trunk connectors TCII in the second oblong 2 in the third connectingr lstage of the first thousand group I. rI`he ten third bank contact sets of the ten second group selectors GSII in the first oblong l of the second connecting stage of the first thousand group are connected to ten trunksl which are multiply connected to the bank contacts of the secondary trunk connectors in the third oblong 3 of the third connecting stage of the first thousand group. and so on.

The ten first bank contact sets of thc sec ond group selectors in the second oblong 2 of the second connecting stage of the first thousand group are connected to ten trunks which are multiply connected to bank contacts of the ten secondary trunk connectors TCII in the first oblong 1 of the third connecting stage of the first thousand group I. The ten second bank contact sets of the ten second group selectors in the oblong 2 of the second connecting stage of the first thousand group I are connected to ten trunks which are multiply connected to bank l'ti (Stn

contacts ot the secondary trunk connectors in the second oblong Q ot the third conneetingg` stage ol the first thousand group l and so on.

The wiring;r between the second group selectors and the secondary trunk connectors in each ot the other nine ditlierent thousand groups is similar.

lt will thus be seen that when an)v second ,fygroup selector has been Set onto a trunk leading' to any one of the ten different oblong's 1-10 or hundred groups of the third connecting stage of the particular thousand group in question the connection will be eX- tended to a wanted line connector WC b v any idle one ot' ten different secondary trunk connectors TCH in the selected oblongy or hundred group.

lt' all the switches in any set of ten primarv trunk connectors TCI should be en- :uged when a call is put through to this set the connection may be extended to the second connectingr stage by an idle primary trunk connector in another oblong or set by arrangements inade for this purpose in accordance with the invention. These arrangements are illust `ated in fl.

At the lett ot this figure two groups ot group selectors GSi and G2@ are shown which correspond to group selectors in the two first oblongs 1 and Q in the ti'st connectinev stage of the tirst thousand group l. yVlie bank contacts of the group selectors tlSi and GISI are connected to trunks which are multiplied in the banks ot the trunk eonnertors Ttll and Ttil in the two tirst eblonggjs of the second eonneetirrur stage ot the first thousand group l. DTI and "'1 are dialling trunk finders and seem'idarf,v trunk linders coordinated to the primariv trunk connectors Tti in the first oblong 1 and DTUSTB are dialling trunk finders and secoi-ulary trunk tinders 1'espe -ti\'el v eo-:nxlinzfited to the secondary trunk connectors in the .second oblong il ot the second comici-ting starre of the first thousand `roup l. 'l`he trunks leading' from the banks ol he froup selectors. instead of being; multiiled in tht` banks ol" the trunk connectors l onl'v two oblongs will. in a 10000 line rwehangfe. he uiultipled in the banks otI the connectors TC in ten oblongs. Ten trunks ein l'roln the group selectors (lt'li of eaeh oblong to each of the ten ditlerert sets ot trunk connectors TCI in the second connect'- in;r stage ot the tirst thousand group l. llenre. the aggregate number ol' trunks emanating; from all the group selectors (lf-li in all of the oblongfs 1. 3 to 10 in the first connecting; stage of the tirst 1000 group is lrtltltl.

In order to enable the switches of any one ot the number of other oblongs. sayv 2. 3. 4 and 5. to be used in case all the switches in an)v particular oblong. say 1 in the second connecting of the first thousand. are all busy`r one or two groups ol' overllow trunk connectors OTC may be provided in the second conneetin;r stage of the first thousand. tt two groups are provided each gfroulp ot overflow trunk connectors ('Yltl may consist of switches whose banks coniprise :"ftl'l bank contact to which one hall' ot the thousand trunks emanatingY Ytrom all ot the group .selectors (2S: are multipl)v coniwcted. tlrerilow diallin;r trunk Vlinders lflll" are associated with the overflow trunk connectors. these finders DTF being! con nef-ted to the overtlow trunks by overtlow trunk tindex-s' UTF. and the overflow trunks being; each associ: lcd with t runk linders ("l`l" which are capable otl eonneetiir;Y to any idle trunk in lire diti'erent ohlonggjs. say 1. 2. Il. 5 in the .second connecting! stapje oi' the ti'rst thousaiul group.

'lhe operation et the orertlemY arrangenr-nt shown in l"i;;, il is as follows: `Wheneier :i Lroup selector. as tlfg. is set onto a trunk leailinf to the trunk connectors et a certain oblong'. as 1 of the second conf nectinf; sfage ot the lirst thousand lgroup. and all ine switches in this group are enezl at that moment. an overflow dialling` t u.; irder ll'l`l" is started and immediate-lv eonnerts the trunk selected by the jioup selector fl/.Fu through to an merllow irn; bv o'l its overflow trunk finder he connaon trunk finders ("Il".

vine; all preselected a tree. talking; trunk. e dialling;` impulses Vfrom the calling suhserilwr will inrniediatelv llow through the s\\.'i'tche1-y Ulft. tl'll". ("illt. to a tree ejronl) selector. as tor emniple litio ot the seeA ond ohiol f in the second comieetinestage of the; il hounnd ffreup. ln the meanf time an overflow truuk connector tl'lltf is est onto the rte'meiliate trunk that has heen selected lo.' a group :wleetor (ltl, and tht` talkinu` connection is then estahli:-:l-ed through an overflow connector (Yltl and :a common trurk finder ("l`l".

The operati-:nis involved in estab:ishinga conne .on beto'eeu two subscribers will now he described in detail with the aid olf ries. n. .rx e", 6'.

llfhen a calling: subscriber t'l raises his re eeiver a circuit is established through the suhscriltens line and the line relay l00'ot the ealliu;v suliserilver is energized b v a eurrent which tlows from the positive pole through 100. cont act .ttll el' the cut-oli rela)v 102, limb ltl olE the suhserihens line.. instrument tl. limb 104 ot the subf-zerihene line. contact 105 ot rela v starting circuit wire 100. snit in;I relav 10i' to the negative pole of the hat ter v. The startingT rela)Y 107 which is conlnion to subscribers ol the one hundred subscribers ot the group to which the callingS subscriber Si belongs is energized and closes its contact 108 to complete a circuit tor the llt) lli

driving magnets 112 and 110 of the two quick-acting calling line finders C1"l and CF a ssociated with the ten'iporarily used dialling trunks allotted to the group of the calling subscriber. The magnet 112 sets one set of wipers 113, 114, 115, 116, 117 of the calling line finder CF1 in motion and the magnet 110 operates the wipers 118, 110, 120, 121, 122 ot the calling line linder CF. The opcrated sets of wipers ot' the two finders CF and CF1 start from different points or numbers in their respective contact banks so that one set ot wipers will reach the calling line before the other, and will be supposed that the wipers 118, 110, 120, 121, 122 reach the calling line first. 'hcn the said wipers are thus set onto the contact set of the calling line a current flows trom the negative pole through a contact 123 ot a release relay 124, contact 125 o1 a relay 126, wire 127, windings ot the hunting relay 128, hunting wiper 121, wire 129, contact 130 ot the energized line relay 100, cut-ott1 relay 102, contact 131 ot the cut-ott relay to the positive pole of the battery. The relays 128 and 102 are thus energized, the relay 128 opening the circuit of the operating' magnet 110 at the contact 132 and the relay 102 cutting a resistance or metering relay 133 into the circuit by opening the contact 131. The metering relay 33 is, however, not energized at this time.

It will be mentioned here that as soon as the wipers of a calling line finder are moved out ot their normal positions the operated magnet, as 110, is energized by a circuit that extends through a contact strip, as 134, and which is independent of the starting wire, as 135. Ttv will also be mentioned that it a subscriber in the second group ot 50 of the group ot 100 subscribers had called a starting relay 107 would have been energized and would have closed a circuit through the operating magnets 100, 111 that move sets of wipers which travel over bank contacts o1'` the second subgroup of 50 in the group of 100 subscribers.

rl`he moment the cut-ol1 relay 102 and the relay 128 are energized as described above the line relay 100 'is disconnected from the line at the contact 101 and the circuit eX- tcnding through thc said relays 102, 128 then extends from the wire 120 through the coutact 136 of thc cutofl1 relay 102 instead ot passing through the contact 130 which is opened on account ot the deenergization of the line relay 100.

The relay 128, in addition to opening the contact 132, also opens the contact 137 and closes contact 138, 190, 140, 141, 142 and theI calling liucl is then extended through the wires 143, 141, wipers 110, 120, contacts 141, 140, wires 145, 146 to the impulse relay 147, which is then energized by a current lowing from the positive pole through the right hand winding of the impulse relay 147 through 145, 141, 11S), 143, 103, S, 104, 144. 120, 140, 146, left hand winding of 147 to the negative pole.

The impulse relay closes the contacts 148 and 149 and a circuit is thus closed which extends from the negative pole through 148 and the release relay 124, resistance 150 to the positive pole. The release relay opens its contacts 151, 123 and closes its contacts 152, 153 and 154, the contacts 152 and 154- being closed before the contact 123 is opened in order to avoid a temporarily de-energization of the relays 128 and 102 which, as described above, receive a current through the contact 123 until the contacts 154, 152 are closed when the current for the said relays will flow from the negative pole through 154, 152, and 127 to 128 and 102.

The closure ot the contact 154 also results in the negative pole being connected to the wire 155 and to a bank contact 156 in the calling line identitier Ic. The closure of the Contact 153 results in the energization of a slow acting relay 126 by a current flowing from the negative pole through 153, 126, resistance 157 to the positive pole ot the battery. The relay 126 on energizing closes a locking circuit for itself at the contact 158, and, at its contact 159, it closes an energizing circuit for the driving magnet 160 of the calling line identifier. The operating magnet 160 then moves the wipers 161, 162, 163 of the identier I0 until the wiper 161 strikes a contact, as 156, connected with the negative pole, when a current flows through the stopping relay 164. to open the circuit ot the operating magnet 160 at the contact 165 and to apply the positive and negative poles ot' the battery to the, wipers 162, 163 through the relay contacts 166, 167.

The prin'iary trunk finders 1)'1, lT1 asvv sociated with the calling line finders CF, CF1 are each arranged so as to preselect di 1`- ferent idle primary trunks as will be more fully described later. It will be assumed that the primary trunk tinder PT has preselected a4 primary trunk so that when the impulse relay 147 was energized as described and closed its contact 14S) a current flowed from the negative pole through 140, contact 169 of the relay 170, wiper 171, bank contact 172, wire 173, wire 174, contact 175 ot the relay 176` wire 177, contact 178, impuls',` relay 179 to the positive pole. 'l`he impulse relay 170 will thus have been energized to close its contacts 180, 181, 182 and to open its contacts 183, 184. The release relay 185 is then ei'iergized by a current which flows from the negative pole through 181, 185, 186 to the positive pole, the said release relay closing ay locking circuit for itselic at the contact 187. A starting current or energizing current also tlows from the negative pole through 187, 188 Contact 189, operating magnet 190, interrupeter 191 to the positive titl pole `of the batte-ryand the Wipers 19:2, 193, 191,195 of the calling line eonnectoror voice current calling line finder CG are then. started and caused to hunt for the line ot the lalling subscriber S who has appropriated the primary trunk P'lhfor his call. The inolnent the line ot this subscriber is reached by the Wipers 192, .193, 191, 195, a current l'lows troni the negativepole through the contact 19T of .the calling line .identil'ier lc, wiper 1923, bank contact 199, wire 19t', wiper 198, wire 199, wire 299, identifying` rclay 199` wiper, 195, identifying wire 1911` bank contact 1921,l wiper 11S, contact 112, wire 19211, hanl; contact 191', wiper 192` contact 199 .to the. positirepole. The identityiug relay 199 .ot' the calling line connector t`t` is thus energized rto open the circuit of the operatinginagnet 19() at the contact 199 and to prepare a circuit for the connecting relay 1T6-at the contact 195. vhile the calling line connector CC, whose wipers will generally take nluch more time to reach the bank contacts ol` the calling line than the wipers ol' the quie i acting calling line tinder 1l". is operating-in the manner described, the calling subscriber S can be sending in his dialling impulses for the purpose ot select ing the wanted group o1E a thousand lines, say the second thousand group. To select the second thousand group the calling sub scriber sets his dial so as to produce two interruptions of the current tiowing .through the impulse relay 11i in quick succession. The. impulse relay 11T is thus caused to open its contact 119 twice so as to gire rise to two deenergizations ot the inipulse relay 179 in quick succession. The relay 179 is thus :tlm deenergiztal twice. to cause two closures olA itv contact 191, whereby two current impulses are caused to llow troni thenegative pole through 19T, 181, 199, operating magnet 119 ot the tirst group selector GSI to the positive pole. The wipers 111, 112', 113', 111, 115 are thus set onto the second baul: contact set ol' the group selector which leads to an intermediate trnnlt i/'l that is connect-A ed to the banks of primary dialling trunl; Iinders DT. 1)'1`1 and to the rbanks ot' prinary trunk connectors TCI located in the wanted thousand group.

'hile. the armatures of the impulse relay 119 are oschlating in response tothe diallingl impulses the changeover relay 11G is niaintained energized by a current that tlows troni the negative pole through 1ST, 119', resistance 11T to the positive pole. But when the impulses cease the contact 182 is maintained closed to-establish a continuous short circuit around the change-over relay 119 and this relay is thus deenergized so that it closes its contacts 11S. 119. The losure oia the contact 11S results in the closure ol the circuit extending 'lroin the negaia'e pole through 11S", contact 129 ol tacis 112,111,119, 1219a1nd 13o while cl g iiscontacts lili and 192. Thenionientthe conA tact 111i is closed the relay 129 is short-eircuited by the negative pole being directly connected to ,the resistance 1.5i' through 123. 13T, 119, 111' and 112. short interval will elapse before the slow-acting relay 129 lets its armature drop bacli to close its contact 123 and to reconnect the negative pole to the wire 12T troni whichthe said pole is disconnected when the armature contacts 152 and 1.31 are opened on the dt energizaiion ol' the release relay 1,21, Ylhns a short interval elapses during which the current lrolu toe negative pole through the lead 2T and the relays 129 and 1923 is interrupted. l'lence, it' the calling` subscriber I' abandons a call before his line has been connected through to a group selector (51 by the ailing line connector CC the two ielays .126 and 191 will both he dcenergized. lint when the calling` line has been connected through to a group selcrtor (151 by a calling line connector CC and the release. relay 121 is deenergiatal on account ot' the energi/ia4 tion o1n the relay 179 as described the relay 12H will he deenergized alone, the energiaation ot the. relay 192 being maintained by a current that tlows Vtroni the negative pole through lt. loof, contact 111, lett hand winding ot the connecting relay 179, contact 112 ol' 119, wiper 191, contact 196, relay 192 and thc relay 133 to the positive pole, the latter relay remainingdeeneig Led.

l.Vhcn the relay 12hl of the quick-acting.;` finder (llC is deenergized as described the .set oll wipers ol the saine that was set onto the calling line is restored to its noriual position by the operating magnet 119 which is energi'fied by impulses that tlow troni the positive pole through the interruptor 1:39', 119, contact '15112. wiper 122, contact strip 131 to the negatiye pole. `il'lufn the wipers 118. 119, 129, 121, 122 reach their normal pte sition the circuit inst described is opened on ac 'ount of the brush 122 leaving the contact strip 131 and contacting with its insulated norinal contat-t that connected to the starting wire lili.

lYhen the release relay 121 is deenergizel the holding circuit (positive pole 1151, 19t. 1519, l-. lot. negative polcll el the calli lig-.e "i c i fried at the een t hier.. i'

lut)

and relay 164 is deenergized to close the contact 165 and thereby make the identitier lo available tor other calls.

The deenergization oit the release relay 12v-1 also results in the primary trunk finder PT being caused to set its wipers unto another primary trunk that is neither' engaged tor a conversation nor seized by another primary trunk tinder lTl. This action ot the primary trunk tinder lT is started, when the release relay 124 is deenergized by a current which tiows trom the positive pole of the battery through contact 151, lett haand winding ot the relay 170 to the negative pole ot the battery. The relay 170 thus energized then closes the circuit otl the operating magnet 152 at the contact 151. The operating magnet then receives impulses which flow from the positive pole through the interrupter 1502, 151, 152 to the negative pole of the battery. The relay 170 is maintained energized as long as the wiper 153 of the primary trunk finder lT strikes bank contacts that are connected to the positive pole o1' the battery, and the contacts encountered by the wiper 153 and that belong to a trunk that has been seized by another trunk inder such as PTl will be connected to the positive pole through a back contact such as 154. The bank contacts encountered by the brush 153 and belonging to engaged trunks ivill be connected to the positive pole by a contact 154 ot the release relay 185 or through contacts 119', 155.

In the intervals during which the Wiper 153 travels from one bank contact to another the relay 170 is kept energized by impulses that iiow from the positive pole through the interrupter 1502, contacts 157, 156 left hand winding ot the relay 170 to the negative pole ot' the battery. As soon as the wiper 158 lands on a bank Contact that is not connected to the positive pole the current flowing through the lett hand winding of the relay 170 is interrupted and relay 170 is deenergizcd whereby the operating magnet 152 is switched ott and the positive pole is connected through the back contact 158 to the wiper 153 and to the corresponding bank contacts o't the seized trunk so as to render this trunk inaccessible to other primary trunk finders.

Arrangements may be prm ided by which, in cases in which all o1l the Ytrunks accessible to the prilnary trunk tinders are engaged, these finders stop in a certain position until trunks become available.

lVhen the release relay 116 was deenergized at the end of a series of dialling impulses as described above the positive pole of the battery was applied to the brush or wiper 114 through 154, 119, 159 and a starting relay 201, Fig. 51, was energized by current that tlows through 114', 160',

starting relay 201 to the negative pole of the battery. The starting relay 201 closes its contact 202 and energizes operating magnets 212 and 210 of primary dialling trunk linders DTl. These dialling trunk tinders are arranged similarly as the calling line linders CF, CF1 and operate to connect the selected intermediate trunk if, through to a secondary trunk tinder such as ST. As the dialling trunk tinders DT, DT were started by the starting relay 201 the dialling trunk tinder DT will connect the intermediate trunk t1 through by means ot its relay 228. The calling line is now connected to the impulse relay 179 which by means ot' its contact 180 energizes the impulse relay 247 by a current that flows through 180, 162 of the relay 163 which is energized in a manner to be presently more fully described, contact 161, Wiper 111', Wire 13', 243, wiper 219, contact 241, winding ot the impulse relay 247 to the positive pole.

The relay 163 was energized at thel moment the intermediate trunk 'itl was reached by the wipers 218, 219, 220, 221 by a current from the negative pole of the battery through 223, 225, relay 228, Wiper 221, wire 229, 229, Wiper' 113, relay 163, contact 119, contact 154 to the positive pole ot the battery. The relay 163 thus energized encloscs a locking circuit for itself through its contact 155 while increasing the resistance in the circuit ot the relay by opening the contact 231.

The relays 226 and 224 ot' the secondary trunk finder ST are energized and the intermediate trunk identitier ltl is appropriated tor the call in an analogous manner to that described in connection with the analogous relays 126, 124 and the calling line identitier I0.

lVhen the impulse relay 247 is energized it closes a circuit at its contact 249 for the impulse relay 279 and the calling subscriber, on sending in his dialling impulses tor the selection ot the wanted hundred group, ca uses the impulse relay 279 to operate and to give rise to energizations ot the operating magnet 210 ot' the second group selector GS11. lVhen the brushes 211, 212', 213', 214 land on the secondary intermediate trunk if that leads to the swvitches` Ttll. DTI, DTII ot' the selected hundred group the starting relay such as 301 is energized by a current that Hows trom the negative pole ot' the battery through 501, 260'. wiper 214, contact 259, Contact 219, contact 254 to the positive pole ot the battery and the starting relay 301 b v closing its contact 302 energizes operating magnets S12, E110 ot the secondary dialling trunk tinders DTI` DTH, in an analogous manner to that described in connection with the relay 201 and the magnets 212, 210 in the DTI is then caused to set one set ot'its' brushes, as 318, 319, 320, 321 onto the secondary intermediate trunk t2 and the impulse relay '347 is thenenergized lby a current which flows from the positive pole through 2,47, 341, 311), 343, 343', 211', 2(31', 202', 280 to the negative pole ot the battery, the contacts'2t2' and 280 being closed by the relays 263' and 279 which are. energizedy at this time, the relay 27S) being energized by current flowing through the closed contact 241) ot the relay 247 or through the contact 278, wire 277, contact 277', wiper 203, wire 2 S', wiper 111', contact 161', 162', 180 to the minus pole ot the battery, and the relay 263 being energized by current tlowing from the positive pole through 255', 263', 213', 321)', wiper 321, relay 328, contact 352, 354 to the negative pole.

The operations of the primary dialling trunk tinders DT, the secondary trunk linders ST and the intermediate trunk identifier lh are analogous to those ot' the calling line finders CF, primary trunk tinders PT and the calling line identitier l.. so that they need not be more fully described here.

The operation ot the primary trunk connector TCI is analogous to that ot' the ailling line connector CC so that a detail description ol' the same is also unnecessary.

lVhen the primary trunk connector TCI has connected the intermediate trunk it through tothe second group selector GS11 the switches DT, UT, and It, are released and revert to common use.

The callin" subscriber having now set the group selectors GSI, Fig. 4" and GS11, Fig. 5b, onto the proper intermediate trunks by his two tirst sets or series of dialling impulses, will now send in a third series ot impulses for the purpose of selecting the desired tens group in the selected 100 group by means ot' the wanted line connector TVC, Fig. The subscribers tens dialling impulses directly atl'ect the impulse relay 17%), Fig. 4h, and are translated by this relay to the relay 279, Fig. b, which, in turn, translates the impulses to the impulse relay 347 associated with the tertiary trunk finder TT which will be assumed to have set its wipers onto the tertiary trunk that interconnects the secondary trunk connector TCU and the wanted line selector or connector YC.

When the impulse relay 347 oscillates the armatures it gives rise to breaks of the circuit that it previously closed through 349, 3139. 371, 372. 537B. 374. 375. 377. impulse elay 379 t0 the positive pole. and the impulse relay 2379 is thus caused to oscillate its armatures so as to send current impulses trom the negative pole ot' the battery through 378 of the release relay 385. (which was previously energized by a current from the negative pole through 381, 385, resistance 386 to the positive pole) 384, contact 400 ot the change-over relay 316' (which is energized by current from the negative pole through 387, $382', 401) 402,'operating magnet 403 ot the tens designating switch Td to the positive pole ot the battery. The operating magnet 403 steps they wiper 404 onto a segment 405 and an arcuate wiper 40G onto bank contacts which are connected lto a normal contact 407 and to teus designatn ing contacts 40S. 409, 410 in the bank of the main switch otl the connector VC. lt' only one tens impulse is .sent in by the calling subscriber only one oscillation otI the impulse relay 17!) will take place and the magnet 403 will step the arcuate wiper 40G onto the: tirst contact 411 of the tens designating switch TJ. The relay 431 will then be energized by a current which flows trom ythe positive pole through 431, wiper 413, normal bank contact 407. bank contact 411. arcuate wipeiI 400 to the negative pole and the operatingl magnet 412 will receive an impulse which flows Yt'rom the positive pole through the interrupter 491, operating magnet 412. contact 434 ot' relay 430, contact 436 otl relay 4231 to the negative pole. and will step the brushes or wipers 413. 414, 415. 410, 417 tor Yard until they reach a tens designatingl contact. 40S, 40S), or 410 etc. which is not connected by the arcuate wiper 406 to the negative pole. ln the case under consideration the arcuate wiper 4013 is only stepped onto the first bank contact 411 so that the wipers 413. 414, 415. 416, 417 will stop as soon as the wiper 413 reaches the long;` bank contact or tens designating contact 40S. when the relay 431 will be dcenergized to open the circuit ot the magnet 412 at 436.

lt the subscriber had sent in two tens selecting impulses the arcuate wiper 400 would have been stepped round so as to apA ply the negatiw pole to the two bank contacts 411, 41S ot the teusy designating` switch. and then the (merating magnet 412 would have continued receiving impulses until the wiper 413 had been driven ot'iA the long` contact 40S onto the second long contact 40E). which corresponds to the second group oi` ten bank contact in thc wanted line connector 1Y0. lil-ach bank contact set comprises a horizontal row ot tour contacts correslionding` to the wipers 414. 415, 410` 417. Only three such bank contact sets are shown in each tens group instead ot` ten tor con .'enience ot illustration.

when the calling subscriber has sent in the tens selecting` impulses a pause will issue during which the impulse relay 379 will keep its armatures steadily attracted.

1t will he assumed that the secondary trunk connector Ttll will` in the meantime, have found the secondary intermediate .titi

trunk 62 and that the dialling trunk lin'der DTI, the tertiary trunk linder TT and the secondary intermediate trunk identilier Itll, which operate in an analogous manner to the corresponding switches in Figs. 5", 5b, have reverted to common use, i. e. have been restored to normal This being' the case the impulse relay 319 o1 the wanted line confnector ll'ty will now he energized by a current tlowiug t'roin the positive pole ol' the battery through 2319. BTT, 31T', 2392, l-ll, 211. 261', 262' 251) to the nec'atire pole ol' the battery.

When the calling: subscriber now sends in his units Cialling;I impulses they will be re ceived directly by the impulse relay 119 and this relay will translate them to the relay 219 which` in turn translates them to the relay 379. During the pause between the tens and units impulses the changeover relay $316 was shortwircuited on account ot the negative pole beingl connected through 3ST, :71H2 to the resistance lrlt so that the changeover relay allowed its armatures to drop back and to close. at the contact 31.543, a circuit extending; Yl'rom the positive pole through 31, upper winding otI relay 12u, wire 421, arcuate wiper 496 to the negative pole. "lhe relay 421) on energizing disconnects the wire 423 lrom the operating' niagnet 493 ot` the tens designating' switch and connects it through 422 to the operating magnet 421 oll the, units designating switi h lid. ll'hen the armatures ot the impulse relay ST9 oscillate in response to the units impulses the operating' magnet 121 is then energized by numerical impulses that tlow lrom the negative pole through 3ST. 21H4, ltlt), 422, 424 to the positive pole and the magnet 424 then steps the wipers 425, 426, 42T around a corresponding' number ot steps. Thus, it three units impulses are sent in by the subscriber the wiper 425 will be eet onto the third bank contact 428 of the units designating switch Ud and the positive pole ol the battery will be applied to the contact 42S through 2315"", 43() and 42:7. lt will be mentioned here that provision is made to prevent the positive pole trom being applied to a bank contact, as 428, ot the units designating' switch until the wiper 413 has been driven otl' the long; contacts 49S, 409 etc. that have been connected to the negative pole by the arcuate wiper 496 of the tens designating switch Til. This provision is made l'or the purpose ot preventingI the stopping' relay 430. that cooperates with the units designating switch Ud by means ofi the wiper 414, troni beingr operated inmecessarily in case units designatingr contacts. as 429. 429. 429/. ol the main switch should have positive battery applied to them before the wipers 41?, 414. 415. 416, 41T of the main switch XVC have been driven into the selected group ol' bank contacts.

The said provision consists in the relay 431 which is energized by a current from the minus pole of the battery through the arcuate wiper 406, long contacts ot the main switch, wiper 413, 431 to the positive pole and is thus caused to open its contact lilo and 432, the Contact 432 and its associated interrupter 491 being provided l'or the purpose ot' assisting,l in restoring' the tens desigeating;A switch Tcl to normal as will be herelnatter more fully described.

When the; wipers 413, 414, 415, 416, `1li' have been driven into the wanted group ot sets ot bank contacts by virtue o1' current impulses flowing from` the positive pole. through 491, 412, 434, 436 to the negat'n e pole, the relay 431 will be` dcenergized and the positive pole tot the battery will be applied through 3182, 430, 425 to the contact 428 and therefore to the units designating contacts 429, 429', 429. As the wiper 414 has travelled past the contacts 429, 429. it will not strike a live bank contact until it. reaches the contact 429 when a current will llow trom the positive pole through $1151", 45t), 425, 428, 429, 414, relay 430 to the negative pole. The energization ot the stopping relay 430 opens at Contact 484I the circuit of the operating magnet 412 which, atter the wiper 413 was driven ot'f the live contacts 498, 499, extended troni the negre tive pole through wiper 421- otl the units designating switch Ud, contact 435, 434,412, 491 to the positive pole. lVhen the wipers 413. 114, 415, 416, 417 are thus stopped on the bank contact set belonging to the wanted line a test circuit is closed at 43T by the stoppin; relay 439. This test circuit extends trem the negative pole through 48T, test relay 438, test wiper 415, a test wire similar to 439 and through the relay associated with the wanted suhscribens` line. 1f the wanted line is busy a busy? tone circuit (not Shown) which extends through contacts ot the relays 430 and 43S and through an inductive winding,` on the relay 379 will be closed and apprise the calling' subscriber' o1l the tact that the wanted line is busy. The calling subscriber will then replace his receiver and the relays 179, 279 and 379 will be deene-rgized. These relays, by means of their contacts 1853, 29?. 9521 will short circuit the release relays 185. 293 and 385 respectively. The relay :95 will then close restoring circuits at its con tacts 446` 441, the one restoring circuit extending` troni the negative pole through the interrnpter 4923, Contact 441, arcuate bank 465, wiper 404, operating, magnet 463 ot the tens designating switch to the positive pole and the other restoring' circuit extending from the negative pole through 4923` 449. wiper 426, arcuate bank contact 442 o1 the units designating switch, operating magnet 424 of this switch to the positive pole. The

operating magnet 424 drives the wipers 425, 426, 427 round until they reach their normal position. The operating magnet 403 drives the wipers 406v 404 around until the wiper 404 leaves thel arcuate bank contact 405. The tens designating switch Td then stops for a while with the wiper 404 on the bank contact 443. The arcuate wiper 406 will now have connected the negative pole to all the long contacts or group designating contacts 406, 409, 410 and hence current will low from the. negative pole through 406, long contacts with which the wiper 413 engages, relay 431 to the positive pole, and this relay will be energized to close a circuit for the operating magnet 412 which extends Jrom the negativo pole through 436, 484, 412, 401 to the positive pole. when the wiper 413 with its associated wipers hasl been driven luto its normal position, that is the position in which the wiper 41?) engages with the bank Contact 407, the circuit of the relay 431, that extends from the negative pole through 406, 410 etc. 413, 431, is opened so that the relay 431 opens the circuit ot the operating magnet 412 at its contact 436 and closes a restoring circuit at 432 which extends from the negative pole through 4911, 432, bank contact 443, wiper 404- operating magnet 403 to the positive pole. The. shape of the wiper 404 and of the contact 4453 is such that this circuit through 403 is opened when the arcuate wiper 406 reaches the normal position shown in which it is out ot contact with the bank contact 411. The wanted line connector XVC will then be Vfully restored to its normal position, the locking circuits of the relays 420 and 430 having been opened at the contacts 367 and 446 rcspectively.

'l' he restoration of the lirst group selector GSi and ot the calling line connector CC takes place as follows: il'hen the release relay 185 is deene-rgized it closes the circuit that cxteinls from the negative pole through interrupter 1202, bank contact strip 1203, wiper 115, wire 1152, contact 1153, operating ini-ignet 110 to the positive pole. This Circuit is maintained until the operating magnet 110 has driven the wiper 115 011 the contact strip 1203 into its normal position. The selector' GSI, whose relay 163 is doenergize-d by the rupture of its circuit at the contact 220 ot the release relay 265 on the next switch ahead as soon as the callingl subscriber hangs up, will now be in its normal position.

The deenergization ot' the release relay 185 in the iirst group selector' GSI also rcsults in the circuit `of the relay 176 and relay 102 being opened at the contact 120. The calling line connector is tl en ready for a new connection without its wipers being stepped into any delinitc normal position.

The reioratien of the second group selector GS11 and of thc primary trunk connector is similar to that of the switches GSI and C "f, so that a detailed description of the operations involved in this restoration is u nn ecessary.

rlhe secondary trunk connector TCH is restored by the circuit of its connecting relay 376 being opened at the contact 320 ot the release relay lt will now be assumed that the tested line is found idle when the est circuit including the test relay 438 is closed by the contact 437 of the stopping relay 430. The test relay 46S will then be energized and at its contact 450 it will immediately close a preliminary ringing circuit which extends from the negative pole through wiper 427 of the units designating switch, contact 450, winding of the ringing relay to the positive pole. The ringing generator 453 will then be immediately applied to the wanted line through the contacts 454, 455, and 456, 457. At the same time a restoring circuit tor the units designating switch will be closed at the contact 458, this restoring circuit extending lrom the negative pole through the interruptor 4914, 458, wiper 426, arcuate bank contact 442, operating magnet 424 to the positive pole. The preliminary ringing current which is thus immediately sent out to the wanted line is interrupted when the units designating switch Utl reaches its normal position in which the prelin'iinary ringing circuit (negative pole, 427, 450, 452, positive pole) is opened by the wiper 427. Ringing current now continues to be applied intermittently by the relay 452 which is intermittently energized by current flowing from the negative pole through the bottom winding of 452, contact 461, contact 451, ringing current interrupter 460 to the positive pole.

.Yhen the wanted subscriber responds a current lows through the relay 462 over a circuit which extends from the positive pole to the lett hand winding of 462, contact 463, contact 456, wiper 417, wanted subscribers station, back to the wiper 416, contact 457, 464, right hand winding of 462 to the negative pole. The relay 462 then opens at its contact 461 the circuit ot the ringing relay and at its contact 465 it closes the cirn cuit of the auxiliary release relay 466, this circuit extending from the positive pole through 465, 466 to the negative pole. T he auxiliary release relay 466 closes a loc-king circuit for itself which extends through the left hand winding of 466, Contact 467 and contact 687. The auxiliary release relay also closes at its contact 468 a metering circuit which extends from the negative pole through the retardation coil 469, 468, wire 469', Contact 470, Wiper 393, wire 3432, wiper 278, wiper 293, wire 293, wiper 112', contact 1803, winding 1813 to the positive pole. The relay 1813 is energized and at its contact 190 it closes a circuit which extends from the positive pole through battery 191,

-ly wire 192, coil 193 of the relay 176 to the negative pole. The coil 193 induces a momentary comparatively strong current in the winding 176 and thus in the circuit ot the relays 102 and 133 and energizes the marginal relay 133 which closes the circuit of the conversation meter at the contact 198. The marginal relay could also be energized by applying a comparatively strong battery directly to the wire 121. The calling subscriber S will now be connected through the contacts of the relays 176, 1813, 2813, 376 to the retardation coil 469 and the impulse relay 379.

If the calling subscriber replaces his receiver irst at the end of the conversation the current flowing through the impulse relay 379 and retardation coil 469 will be interrupted and the impulse relay will short circuit the release relay 385 at the contact 381. The tens designating switch TD and the main switch IVG will then be restored as already described by restoring circuits extending through the contacts 441, 405, 404 and afterwards through the contacts 432, 443 and wiper 404. IVhen the release relay 385 opens at contact 320 the relays 376 and 263 will be deenergized, the latter relay opening` the circuit of the impulse relay 279 at the contact 262. The impulse relay 279 will then short circuit the release relay 285 which will close the restoring C11-@uit 2202, 2202, 215', 2153, 21o of uw second group selector, while opening the circuit of the relay 276 and also of the relay 163 at the contact 220. The relay 163 is thus deenergized and at its Contact 162" it opens the circuit of the impulse relay 179 which then short circuits the release relay 185, this relay thereupon closing the restoring circuit of the first group selector GSI at 1153 and opening its contact 120 so as to deenergize the relays 176, 102, 133.

If the wanted subscriber replaces his receiver first at the end of the conversation the relay 462 will be deenergized and close the contact 490 so as to apply the positive pole through 490, 491 directly to the resistance 386. The release relay 385 is thus short circuited and initiates the disconnect which proceeds in the manner already described.

I claim :a

1. In an electro-mechanical telephone system, groups of subscribers lines, primary talking trunks, secondary talking trunks, intermediate trunks between the primary and secondary trunks, a numeral selector associated with each said primary talking trunk, a non-numerical switch associated with cach said secondary trunk, auxiliary trunks, auxiliary non-numerical switches adapted to connect an auxiliary trunk to any selected intermediate trunk and to any idle secondary trunk, and means for extending a call from a subscribers line through a primary talking trunk, a numerical selector, and through an intermediate trunk and a secondary trunk connected to a said auxiliary trunk.

2. In an electro-mechanical telephone system, groups of subscribers lines, primary talking trunks, secondary talking trunks, intermediate trunks between the primary and secondary trunks, a numeral selector' associated with each said primary talking trunk, a non-numerical switch associated with each said secondary trunk, auxiliary trunks, auxiliary non-numerical switches adapted to connect an auxiliary trunk to any selected intermediate trunk and to any idle secondary trunk, means for extending a call from a subscribers line through a primary talking trunk, a numerical selector, and through an intermediate trunk and a secondary trunk connected to a said auxiliary trunk, and means for disconnecting the said auxiliary trunk when a connection through the intermediate trunk and the secondary trunk is established.

3. In an electro-mechanical telephone system, group selectors, talking trunks, and finders each with a plurality of simultaneously hunting wipers for extending connections from the bank contacts of the group selectors to the said talking trunk.

4. In a telephone system, connectors each consisting of a rotary step-by-step switch with bank contacts connected to wanted lines and two auxiliary numerical switches adapted to steer the wipers of their associated switch onto a wanted line.

5. In a telephone system, connections each consisting of a rotary step-by-step switch with bank contacts connected to wanted lines and two auxiliary numerical switches adapted to steer the wipers of their associated switch onto a wanted line, and test circuits for testing a line onto which the wipers of the connector have been steered.

6. In a telephone system, connectors each consisting of a rotary step-by-step switch with bank contacts connected to wanted lines and two auxiliary numerical switches permanently associated with each connector and adapted to steer the wipers of their associated switch onto a wanted line, test circuits for testing a line onto which the wipers of the connector have been steered, and ringing means controlled by one of said auxiliary switches.

7. ln a telephone system, connectors each consisting otl a rotary step-by-step switch with bank contacts connected to wanted lines and two auxiliary numerical switches adapted to steer its wipers onto a wanted line, and ringing means controlled by one ot said auxiliary switches.

8. In a telephone system, connectors with bank contacts connected to wanted lines, two auxiliary numerical switches permanently associated with each connector and adapted to steer its wipers onto a wanted line, and connector restoring means controlled by a said auxiliary switch.

9. In an electro-mechanical telephone system, groups of subscribers lines, primary talking trunks, secondary talking trunks, intermediate trunks between the primary and secondary trunks, a numeral selector associated with each said primary talking trunk, a non-numerical switch associated with each said secondary trunk` auxiliary trunks, auxiliary non-numerical switches adapted to connect an auxiliary trunk to any selected intermediate trunk and to any idle secondary trunk, and means for extending a call from a subscribers line through a primary talking trunk. a numerical selector, and through an intermediate trunk and a secondary trunk connected to a said auxiliary trunk. the said auxiliary non-nnmerical switches being divided into switches having contact banks with Jfewer bank contacts than the banks of the non-numerical switches associated with the said secondary trunks.

10. In an electro-mechanical telephone system, groups of subscribers lines, primary talking trunks, secondary talking trunks, intermediate trunks between the primary and secondary trunks, a numeral selector associated with each said primary talking trunk, a non-numerical switch associated with each said secondary trunk, auxiliary trunks, auxiliary non-numerical switches adapted to connect an auxiliary trunk to any selected intermediate trunk and to any idle secondary trunk, means for extending a call from a subscriber`s line through a primary talking trunk, a numerical selector, and through an intermediate trunk and a secondary trunk connected to a said auxiliary trunk, and overflow switches with bank contacts connected to the banks ot a plurality of groups of secondary non-numerical switches.

ll. In a telephone system, connectors with bank contacts connected to wanted lines, two auxiliary numerical switches perm'anently associated with each connector and adapted to steer its wipers onto a wanted line, and ringing means controlled by a wiper of one ot said auxiliary switches.

1:2. In a telephone system, connectors with bank contacts connected to wanted lines, two auxiliary numerical switches permanently associated with each connector and adapted to steer its wipers onto a wanted line. and connector restoring means controlled by a wiper of one ot said auxiliary switches.

In testimony whereotl I have affixed my signature.

FRITZ ALDENDORFF.

CERTIFICATE 0F CORRECTION.

Patent No. 1,541,779. Granted .lune i6. |925, t0

FRITZ ALDENDORFF.

lt is hereby certified that the above numbered patent was erroneously issued to Paul Kolisch, of New York, N. Y., as assignee of the entire interest in said invention, whereas said Letters Patent should have heen issued to the inventor, said Aldendorff, and Pani Kolisch, said Kolisch being assignee of one-quarter interest only in said invention, ns shown by the records of assignments in this office; and that the said Letters Patent should he read with this correction therein that the same may conform to the record of the ease in the Patent Office.

Signed and sealed this 24th dav of May. A. i). i927.

M. J. Moore, Seal. Acting Commissioner of Patents. 

